Merge pull request #6166 from cbednarski/docs-checkpoint

Change docs for checkpoint environment variable

website/docs/source/v2/other/environmental-variables.html.md

@@ -25,6 +25,9 @@ calls over the internet for any reason can be undesirable. To surpress these
 calls, set the environment variable `VAGRANT_CHECKPOINT_DISABLE` to any
 non-empty value.
 
+If you use other HashiCorp tools like Packer and would prefer to configure this
+setting only once, you can set `CHECKPOINT_DISABLE` instead.
+
 ## VAGRANT\_CWD
 
 `VAGRANT_CWD` can be set to change the working directory of Vagrant. By